<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        div li{
            color: red;
        }
        .center>li{
            color: blue;
        }
        span,p{
            color: pink;
        }

    </style>
</head>
<body>
<div>
    <ol>
        <li>aa</li>
        <li>bb</li>
    </ol>
</div>
<div class="center">
    <li>儿子</li>
    <ol>
        <li>孙子</li>
        <li>bb</li>
    </ol>
    <span>span</span><br/>
    <p>p标签</p>

</div>

</body>
</html>